Function find_dep_kind_root 

pub(crate) fn find_dep_kind_root<'tcx>(
    tcx: TyCtxt<'tcx>,
    id: QueryJobId,
    job_map: QueryJobMap<'tcx>,
) -> (Span, String, usize)

Finds the query job closest to the root that is for the same query method as id (but not necessarily the same query key), and returns information about it.